LONDON, (AFP) - The legend of the Scottish Loch Ness monster may be explained by earthquakes, an expert said Wednesday. Decades of argument about whether the lake is inhabited by a dinosaur-like monster may be ended by a new theory advanced by Italian geologist Luigi Piccardi.

Loch Ness rests along the Great Glen Fault, a major fault line in the Earth's crust which was responsible for a major quake as recently as 1901. Piccardi is convinced that shocks along this fault lie behind both ancient and modern reports of the monster. The tremors would cause the ground to shake, produce a roaring sound, and release bubbles of gas to churn up the calm surface of the loch. Try this Loch Ness webcam to have a look yourself.

Stories of the monster date back to the seventh century, when a water beast is said to have appeared with strong shaking before Saint Columba, the founder of Christianity in Scotland.

The most seismically active end of the loch is the north end. This corresponds to the site where Saint Columba encountered the monster, and also where many modern witnesses claim to have had experiences.

In these reports people don't usually describe seeing the beast itself. More often they talk of seeing a lot of commotion on the water, and hearing loud noises, and they assume it to be caused by the monster. But it could be due to a small shock and gas emission, he said.

When visual sightings did occur they usually reported humps emerging from the water, said Piccardi. But these, too, could be the result of anomalous waves produced by gas bubbling up to the surface.

Piccardi is one of a number of experts attending Earth System Processes, a symposium in Edinburgh organised jointly by the Geological Society of London and the Geological Society of America. He has already argued that many Greek myths originate from earthquakes.